Studying all night for a college exam? You might get a better grade by sleeping instead.
Exam week on a college campus looks the same anywhere: bleary-eyed young adults stumble to and from the library, lugging bulging bags of books while on the lookout for the nearest vending machine of energy drinks. Students pop caffeine pills and attention-enhancing medication, straining to hold their eyes open at 3 a.m. as they try to absorb a textbook’s worth of information.

However, students who engage in all-night cramming sessions may, in fact, be putting their grades in jeopardy. Sleep plays an essential part in learning and memory recall, and taking exams while sleep deprived may be worse than not studying at all.

New, unique information that a student learns from a book or lecture is temporarily stored in the brain’s short-term memory. Scientists estimate that the average short-term memory can hold between four and seven “chunks” of information, depending on how the student links or arranges the information. Many scientists believe sleep plays the primary role in transferring that information to long-term memory. They theorize that during sleep, the brain consolidates memory, arranging and storing data in ways that can be easily recalled later.

A well-rested brain also recalls information faster and more accurately with less effort. A 2008 study on sleep and cognitive performance revealed that sleep-deprived subjects had difficulty recognizing images studied the day before, while rested subjects performed well on the test.

How well one pays attention to a lecture or textbook depends greatly on sleep. Well-rested students can not only focus better in class, they can also maximize their short-term memory storage by grouping information into larger chunks. Post-learning sleep causes an increase in blood flow to areas of the brain used in learning, and a rested student may master tasks more quickly with less practice. Therefore, a good night’s sleep may actually reduce the need for lengthy study sessions.